So I'm a 14 year old freshman, and to give you a sense of my build I'm 6' 3", 160lbs(Still growing, so please don't say loss weight). Last year in middle school I was a 400 and 800 runner, with PBs of 54 and 2:08. Not great, but pretty good for someone my age. Now had run a 4:50 mile as well, but I am a speed guy. I decided to do cross country this year. I knew I wouldnt be a star of the team, but I suck. I'm dying after about 1.5 miles into a 5k and I'm struggling to break 20. I'm getting beaten by friends who were only 5:25 milers last year. I'm doing the same mileage as them but I keep getting destroyed. To make sure I haven't just gotten slower over the summer I went to the track to run a 400 and I went 55 with almost no speed work since spring, so I know thats not the answer. Please help.